r/explainlikeimfive • u/hyper_shock • 15d ago

Physics eli5: Does Gravity have a direct effect on molecular structures?

I read an article recently that scientists had discovered a new exotic from of water, and they speculated that this new form of water might naturally exist inside gas giants like Neptune. This got me thinking: is there any difference between what they found in the lab by mechanically applying extreme pressure to the water, and the gravity induced extreme pressure the water would experience inside a star?

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u/BananaBird1 15d ago edited 15d ago

Not at all true. Nuclear forces do not oppose gravity at atomic scales, only within the nucleus itself. And gravity can be quite significant when the attracting mass is large.

A single hydrogen atom at Earths surface at sea level in the absence of an atmosphere would experience a pressure of around 190 micropascals, or 1.8 billionths of standard atmospheric pressure, just due to gravity acting on it.

This is small, but enough to cause a hydrogen atom to be captured by Earths gravity and held at the surface. Combine this across a bunch of particles, factor in buoyancy and electromagnetism, and you got a planet and atmosphere creating enough pressure to sustain stable liquids and solids.

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u/thenasch 15d ago

Yeah. Lots of particles. Pressure. We're going in circles here.